Zombie Satellite Causes Astronomical Buzz

Yahoo ^ | 5-11-10 | Claudine Zap

[Vaquero]

Don't be alarmed. High above your heads, a zombie satellite is on the loose. OK, actually, it won't really be a bother to us earthlings. Or at least to most of us. (More on that later.) But the rogue communications satellite is wreaking havoc in Earth's orbit and does threaten to interfere with signals coming from other satellites. Here's the backstory...

[Vaquero]

Zombie Satellites???

Oooooooooo.....SCARY!!!!

[Vaquero]

Ping

[Vaquero]

[Jonah Hex]

Image of rogue satellite captured by Hubble telescope:

[Tallguy]

OK. Somebody explain how a communication satellite ‘wanders’ from its assigned orbital position? Isn’t Isaac Newton in the driver’s seat? These things are in geostationary orbit, so it’s not like atmospheric drag could be the culprit. Did it somehow fire a steering thruster when it ‘died’?

And if this was a solar flare that killed the sat, why didn’t the communications payload get ‘fried’ in the process? Doesn’t make a whole lot of sense.

[raybbr]

OK. Somebody explain how a communication satellite ‘wanders’ from its assigned orbital position? Isn’t Isaac Newton in the driver’s seat? These things are in geostationary orbit, so it’s not like atmospheric drag could be the culprit. Did it somehow fire a steering thruster when it ‘died’?

That's one possibility. It could have been hit by space debris that threw it off.

[csvset]

Someone will have too call the space tow truck to haul this clunker to the junkyard.

Hey, it sounds like an idea for a Sci-Fi story.

[raybbr]

Actually...

But instead of just dying and drifting off, the satellite has continued to orbit the Earth, even though it refuses to receive instructions from its owner, Intelsat.

Apparently the real problem is that it's still in its orbit and "stealing" sat communications.

[Jonah Hex]

Possibly a thruster mis-fire. Also possibly a micro-meteor hit. If it it kicked in a bit of retrograde velocity, then you'd get an orbit with an apogee at GEO and a perigee approaching LEO.

Don't know the facts, just hazarding a guess...

[G Larry]

When you burn your finger, does your foot still work?

[scoobysnak71]

>"a zombie satellite is on the loose."

So what? We've had one in the White House for years.

[silverleaf]

ROFL! Thats some modified death star.
Does it home in on FOX news?

[Moonman62]

From some article on the Internet:

The main source of perturbation for a satellite in GSO is the combined gravitational attractions of the Sun and Moon, which causes the orbital inclination to increase by nearly one degree per year. This is countered by a north-south station-keeping maneuver about once every two weeks so as to keep the satellite within 0.05° of the equatorial plane. The average annual velocity change (delta v) needed is about 50 m/s, which represents 95% of the total station-keeping propellant budget. Additionally, the bulge of the Earth causes a longitudinal drift, which is compensated by east-west station-keeping maneuvers about once a week, with an annual delta v of less than 2 m/s, to keep the satellite within 0.05° of its assigned longitude. Finally, solar radiation pressure caused by the transfer of momentum from the Sun's light and infrared radiation both flattens the orbit and disturbs the orientation of the satellite. The orbit is compensated by an eccentricity control maneuver that can sometimes be combined with east-west stationkeeping, whereas satellite's orientation is maintained by momentum wheels supplemented by magnetic torquers and thrusters. Ion propulsion systems, notably XIPS, are being used increasingly for station-keeping.

[Eepsy]

I thought everyone knew that any satellites that accidentally go out of their announced orbits are, in actual fact, secret CIA/KGB/MI5 spy cameras scoping out ChiComs/CapitalistOppressors/WorldCupFootie.

Or have I been reading too much Tom Clancy?

[Jonah Hex]

Or have I been reading too much Tom Clancy?

Dale Brown. ;-)

[Lucky Dog]

OK. Somebody explain how a communication satellite ‘wanders’ from its assigned orbital position? Isn’t Isaac Newton in the driver’s seat?

Suggest you research solar wind, oblate spheroid shape of the earth, n-body problem, micro-meteors, for starters on your question about Isaac Newton.

Did it somehow fire a steering thruster when it ‘died’?

Possible... Additionally, the article uses the term "fried" referring to the controlling hardware/software of the satellite ground control order reception/execution system. This scientific term could have referred to anything from a simple break in a single circuit to a completely melted chip. The point is that depending upon the circuit's physical placement, shielding, circuit redundancy, program fault tolerance, etc., it vulnerability to an external disruption (either physical material like a micro-meteor or radiation from a solar flare, etc.) could be greater than the communication circuitry. Additionally, the programming in the control program would probably have been much more complex in the execution loops and thus more vulnerable to information/coding loss. Such a loss could have been responsible for an errant command to fire a thruster, loss of command signal processing or execution, etc.

[GeronL]

ping

[6SJ7]

I’m reminded of the opening scene in “Wall-E” where the camera zooms down toward Earth thru a cloud of dead communication satellites still in orbit.

[Constitution Day]

Stay away from that Obama Death Star!

[a fool in paradise]